In the Gram stain, gram-positive bacteria are dark purple for all the following reasons EXCEPT: None of the other four answers (All are reasons that gram-positive bacteria are purple Crystal violet is fixed inside the cell as a CV-lodine complex once iodine is added The counterstain (safranin) causes the purple color to develop The primary stain, crystal violet, is dark purple Thick peptidoglycan in the gram-positive cell wall prevents decolorization by alcohol

In the Gram stain, gram-positive bacteria are dark purple for all the following reasons EXCEPT: None of the other four answers (All are reasons that gram-positive bacteria are purple Crystal violet is fixed inside the cell as a CV-lodine complex once iodine is added The counterstain (safranin) causes the purple color to develop The primary stain, crystal violet, is dark purple Thick peptidoglycan in the gram-positive cell wall prevents decolorization by alcohol

Basic Clinical Laboratory Techniques 6E

6th Edition

ISBN:9781133893943

Author:ESTRIDGE

Publisher:ESTRIDGE

Chapter7: Basic Clinical Microbiology

Section7.7: Bacterial Identification And Antibiotic Susceptibility Testing

Problem 2RQ

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In the Gram stain, gram-positive bacteria are dark purple for all the following reasons EXCEPT: The primary stain, crystal violet, is dark purple The counterstain (safranin) causes the purple color to develop Thick peptidoglycan in the gram-positive cell wall prevents decolorization by alcohol Crystal violet is fixed inside the cell as a CV-Iodine complex once iodine is added None of the other four answers (All are reasons that gram-positive bacteria are purple
When performing a Gram stain on a Gram-negative bacteria, why does the bacteria stain pink? Crystal violet stain binds to iodine and remains in the bacterial cell wall because of the thick peptidoglycan layer. Safranin counterstain gets in the bacteria’s cell wall to stain the cell pink. The alcohol wash removes crystal violet and iodine from the bacteria. Crystal violet stain binds to iodine and remains in the bacteria cell wall because of the thick peptidoglycan layer AND Safranin counterstain gets in the bacteria’s cell wall to stain the cell pink. Safranin counterstain gets in the bacteria’s cell wall to stain the cell pink AND The alcohol wash removes crystal violet and iodine from the bacteria.
Janet is doing a Gram stain on a mixed culture that is known to contain both Gram positive and Gram negative bacteria. After finishing, she realizes she mixed up the safranin and alcohol steps. What is likely to be observed when she views the slide under the microscope? All cells will appear purple, regardless of whether they are actually Gram negative or Gram positive. All cells will appear pink, regardless of whether they are actually Gram negative or Gram positive. Gram negative cells will be clear, Gram positive cells will be purple. Gram positive cells will be clear, Gram negative cells will be pink. Cells will appear clear, regardless of whether they are actually Gram negative or Gram positive.
When you interpret a Gram-stained smear, you should also describe the morphology (shape) of the cells, and their arrangement. In the figure below, there are two distinct types of bacteria, distinguishable by Gram stain reaction, and also by their shape and arrangement. Below, describe these characteristics for both bacteria: Gram positive bacterium Gram negative bacterium Morphology cocci bacillus Arrangement
Bacillus subtilis (Gram-positive) and Pseudomonas aeroginosa (Gram-negative) bacteria are heat-fixed on slide and subjected to Gram staining. What do you observe under the microscope when the following steps are skipped? Please explain.a. Staining with safraninb. Staining with Gram iodinec. Decolorization
You accidentally switch the Crystal violet and Safranin steps during your Gram stain. When you look under the microscope, what color will a Gram positive bacteria, like Staphylococcus aureus, be? Red/Pink Purple colorless
Why is it necessary to use a 24-hrold culture in gram staining? What does Gram staining reveal owing to its use in clinical diagnosis? Indicate color staining results of gram positive and negative bacteria for every hypothetical scenario. Modification in Procedure Staining results 1. Crystal violet was replaced with methylene blue. G+ G- 2. Mordant was skipped G+ G- 3. Decolorizing step was omitted G+ G- 4. counterstain was not used? G+ G- 5. Crystal violet and safranin was swapped in position. G+ G- What bacterial specimen represent the following: (a) positive simple staining; and (b) negative simple staining viewed under OIO. Provide details such as specimen and bacterial stain used and reference. Positive Staining 1000 X Negative Staining 1000 X
You accidentally switch the Crystal violet and Safranin steps during your Gram stain. When you look under the microscope, what color will a Gram positive bacteria, like Staphylococcus aureus, be? a)red/pink b)purple c)colorless
What staining technique is used here? What is the primary stain, decolorizing agent, and counter stain of this technique? Do we heat fix in here? Describe the organism with the blue color. Describe the organism with the bright pink color. Name the genus of bacteria with bright pink.
For each of the following stains, list each of the chemicals used (in order), briefly describe what you would observe under the microscope, and list examples for each. - Gram stain (list color and example for Gram + and Gram -) - Acid Fast (list color and example for Acid Fast + and -) - Negative Stain (list color of organism stained with negative stain) - Capsule Stain (list color and example of organism with capsule) - Spore stain (list color and example of spore and cell)
The acid-fast bacterium, Mycobacterium smegmatis, is relatively safe to be used by students in performing the acid-fast stain technique because of its thin cell wall. However, if this organism is used for Gram-stain, it can also take the Gram stain reaction. Why is this so?
Which one of the following statements about the Gram stain is false? A-In the Gram stain, a dye called crystal violet is used to stain the cells purple. B-Gram positive cells end up being stained purple. C-Gram negative cells have thinner peptidoglycan layers than Gram positive bacteria. D-In the Gram stain, alcohol is used to kill the bacteria E-Gram negative cells end up being stained pink or red.